There is a general trend towards miniaturisation of portable electronic devices, including portable wireless devices. As a result, antennas compete for space with the other device components (e.g. battery, display, keypad, printed circuit board).
In addition, modern wireless systems demand increasingly greater bandwidths in order to accommodate higher data rates. This is particularly true of video and audio applications that use the Ultra-Wideband (UWB) protocols being standardised by the IEEE. However, the goals of reduced physical size and increased bandwidth are not normally compatible. Further, reducing the physical size of the antenna normally tends to reduce the radiation efficiency of the antenna.
It would be desirable, therefore, to provide an antenna which, physically, is relatively small while satisfying relatively large bandwidth requirements and radiation efficiency requirements.